Move convertViewportToWindow and convertWindowToViewport from

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
index 94998553c237f4f7d762068c5eb7d4e9b42a1978..422ea350ec79de6b97da87b374ba973c6ecf38f8 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.h
@@ -60,7 +60,7 @@ enum IncludeScrollbarsInRect {
 class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin {
     WTF_MAKE_NONCOPYABLE(ScrollableArea);
 public:
-    static int pixelsPerLineStep(HostWindow*);
+    static int pixelsPerLineStep(HostWindow*, Widget*);

[dcheng, 2016/09/08 05:25:47]

Oh... I guess it's because of this. So I guess we need to move the frame tree /
WebWidgetClient into public/platform first.

[lfg, 2016/09/08 21:40:43]

Acknowledged.

     static float minFractionToStepWhenPaging();
     static int maxOverlapBetweenPages();
 
@@ -292,7 +292,7 @@ protected:
     ScrollableArea();
 
     ScrollbarOrientation scrollbarOrientationFromDirection(ScrollDirectionPhysical) const;
-    float scrollStep(ScrollGranularity, ScrollbarOrientation) const;
+    float scrollStep(ScrollGranularity, ScrollbarOrientation);
 
     void setScrollOrigin(const IntPoint&);
     void resetScrollOriginChanged() { m_scrollOriginChanged = false; }
@@ -318,7 +318,7 @@ private:
     // This function should be overriden by subclasses to perform the actual scroll of the content.
     virtual void setScrollOffset(const DoublePoint& offset, ScrollType) = 0;
 
-    virtual int lineStep(ScrollbarOrientation) const;
+    virtual int lineStep(ScrollbarOrientation);
     virtual int pageStep(ScrollbarOrientation) const;
     virtual int documentStep(ScrollbarOrientation) const;
     virtual float pixelStep(ScrollbarOrientation) const;